1 Field of the Invention
The present invention relates to a fume apparatus, and in particular to a fume hood apparatus with a rotatable airfoil member that improves the containment performance of the fume hood apparatus and reduces the probability of the occurrence of spills, thereby improving safety during operation of the fume hood apparatus.
2 Description of the Related Art
Fume hoods are protective enclosures that provide ventilated and illuminated workspaces for laboratory or other applications. A fume hood in its most basic form is a box with an inlet and an outlet. The inlet generally has a movable sash capable of moving vertically or a combination of vertically and horizontally, which provides an opening that allows access to the workspace. The procedures performed inside the fume hood are exhausted at the back through the top of the fume hood to a heating, venting and air conditioning (HVAC) system.
In some fume hood designs, an airfoil is mounted in a pivotal manner at the front of the work surface. Typically, the airfoil is flush or coplanar with the fume hood""s work surface to provide a substantially unobstructed path for moving items in and out of the fume hood. When the airfoil is rotated to an up position, the direction of the airflow pattern is changed to improve the containment of airborne contaminants. However, there is a problem with a raised airfoil in that the technician may accidentally catch an item, for example, a beaker on the edge of the airfoil when the technician is removing the beaker, thereby increasing the probability of a spill.
The inventors of the present invention have recognized that it is beneficial to automatically rotate the airfoil up and down when the sash is lower than a predetermined height and so as to minimize the potential for a spill when the technician is removing items from the workspace of the fume hood.
The present invention comprises a fume hood apparatus including an enclosure, a movable sash and an airfoil member for directing airflow through the opening and along the fume hood""s work surface. The airfoil member is automatically raised to a first position when the movable sash is positioned above a predetermined height above the bottom of the fume hood apparatus to effectively evacuate the work surface and the workspace of fumes and other waste materials. When the movable sash is positioned at or below the predetermined height, the airfoil member is automatically lowered to a second position that is flush or co-planar with the work surface, thereby minimizing the possibility of an accident when the technician removes an item from the workspace. Also, the airfoil member can be automatically raised or lowered when a velocity of the airflow through the access opening decreases below a predetermined value.
In another aspect of the invention, the airfoil member includes one or more fins for directing the airflow through the opening and along the work surface. The fins may include one or more angled portions such that a portion of the airfoil member is positioned below the work surface when the airfoil members are in the second position.